Electrical resistor mounting structure



July 6, 1954 P. R. BuRRows ELECTRICAL RESISTOR MOUNTING STRUCTURE Filed Dec. '5, 1950 l INVENTOR ATTORNEY Patented July 6, 1954 ELECTRICAL RESISTOR MOUNTING STRUCTURE Philip R. Burrows, Naugatuck, Conn, assignor to The Bristol Company, Waterbury, 001111., a corporation of Connecticut Application December 5, 1950, Serial No. 199,225

7 Claims. 1

This invention relates to mounting means for enclosed resistors of the ballast resistance type. More particularly it relates to mounting means for insuring a stable and permanent relation between the resistance elements and their supporting means.

For many years it has been the common practice to enclose electric resistance elements in evacuated envelopes in order to prevent disintegration of the elements when they are heated to elevated temperature where oxidation effects are increased. In making resistors of this type it is necessary to wind the resistance wire on electrically insulating supports so as to prevent short-circuiting of the turns of the wire which are usually wound in a more or less zigzag configuration on the support. The wires used for this purpose are filamentary in character and are extremely fragile, and it is therefore necessary that they be subjected to a minimum of stress during their assembly and use. It has been the common practice to provide a plurality of spaced. disc-like insulators having slits in their peripheral edges, and to wind the wire in a continuous filament in these slits back and forth between the spaced discs in alternation. When the assembly is new the results are satisfactory and the elongation of the heated filaments is usually insufficient to cause them to be detached from their supports. When, however, the filaments have been in use for a long time and are subjected to periodic heating and cooling, the filaments may become detached from their support, especially when subjected to vibration, so as to short-circuit certain of the turns and render the whole structure useless.

The present invention is concerned with a method. of preventing the detachment of the filaments from their support without in any way interfering with their normal structure and operation.

One object of the invention is therefore to provide means for securing resistance elements to the insulating support in an evacuated tube.

Another object of the invention is to provide securing means which is itself an insulator and capable of application to the structure during the assembly of the same.

Other objects and advantages of the invention will be apparent from the following specification when it is read in connection with the accompanying drawings in which Figure 1 is a perspective view of a ballast tube embodying the present invention and showing the enclosing envelope in section;

Figure 2 is a plan view of one of the insulating supports shown in Figure 1, indicating how the securing means is placed in position, and

Figure 3 is an enlarged detailed view of the securing means, the section being taken on line 33 of Figure 2.

Referring to Figure 1, reference character 4 designates a tube base of conventional type having the usual prongs 5. Afixed to the base 4 is a glass or other sealing envelope 6 which may be evacuated in the usual manner. Mounted within and secured to the base 4 is a glass mounting means 7 having embedded therein, in spaced relation, metal supporting studs 8, 9 and I0. Threaded over these studs in spaced relation to each other are two supporting discs ii and i2 fixedly held thereon. In practice the discs 5! and I2 may be of identical structure so that the description of one will be sufficient. Accordingly it may be said that the disc H, for example, is composed of mica, glass or other electrically insulating material, having a plurality of wide slots l3 cut in its periphery, and connecting with spaced circular openings Hi. In this way the slots are separated by protuberances l5, forming separators for the individual turns or strands of the resistance wire [6 which make up the resistance elements of the tube.

Solely by way of illustration the resistance wire it is shown electrically connected to rods 5 and I0, the rod 9 not forming a part of the electric circuit. Consequently, as shown, the wire it": passes through one of the openings H in disc I! and then downwardly parallel to rod Iii through a similar opening in disc !2, over the bottom of the protuberance l5 adjoining the opening in the bottom disc, and then back up to an opening in the top disc, this threading arrangement being continued until the filament wire terminates and is connected to the rod 3. The wire thus zigzags between the spaced discs as indicated in Fig. 3 and presents the appearance of a cylindrical cage as seen in Fig. 1.

The structure so far described is more or less standard and is subject to the failures above indicated when the wire It becomes heated. The result is that the wire may become detached from. the protuberance [5 in spite of the existence of the openings 14 and the slots l3.

According to the present invention such failures are completely obviated by securing the filament wire 16 within the openings i4 through the use of a ceramic filament of insulating ma-- terial such as a glass thread H. This glass thread is wound over and under the protuberance it, as shown in Figures 2 and 3 in such a way as to engage the filament wires [6 between the two discs H and I2 by in eflect encircling the cylindrical resistance wire cage at the disks and thus prevent the resistance wires from sliding off the protuberances. In other words the ceramic filaments embrace the resistance wire and confine it to the openings in the discs.

Inasmuch as the securing filament H is an electrical insulator it does no harm for it to contact filament wire [6, and yet it is fully efiective to prevent the filament wire from escaping from its support regardless of the amount of elongation or sagging that may occur.

It will be apparent that the present invention solves in a very simple manner a troublesome problem, and that it is applicable to numerous types of structures regardless of the particular structural characteristics of the disc or the resistance wires. While it has been indicated that the envelope is evacuated, it will be obvious that it may be filled with an inert gas suchas nitrogen or the like, in order to assist to a maxi mum degree in the protection of the heated filamerit from deterioration. It will also be apparent that whereas reference has been made to a ceramic filament of insulating. material in the form of a glass thread, numerous other insulating m terials might be substituted.

Accordingly, while only one embodiment of the invention has been illustrated, it will be obvious that numerous changes and modifications may be made in the details within the scope of the claims Without departing from the spirit and scope of the invention.

Having thus described my invention, what is claimed is:

l. A ballast tube comprising an evacuated sealed envelope having a plurality of spaced insulating supports therein, said supports having wire receiving slots, resistance wire means bridging said supports and threaded through said slots,'and flexible ceramic filament means securing said resistance wire means to said supports.

2. A ballast tube comprising an evacuated sealed envelope having a plurality of spaced insulating supports therein, resistance Wire means engaging and bridging said supports and being Wholly supported thereby, and flexible ceramic filament means securing said resistance wire means to said supports.

3. A supporting structure for electrical resistance elements, comprising a plurality of coaxial spaced discs having peripheral slots, a resistance wire wound in zigzag fashion in said slots and alternating between said discs, and a ceramic filament in said slots for securing said resistance wire to said discs.

4. A supporting structure for electrical resistance elements, comprising a plurality of coaxial spaced discs having peripheral slots, a resistance wire wound in zigzag fashion in said slots and alternating between said discs, flexible ceramic filament means securing said resistance wire to said discs, and an envelope enclosing said structure.

5. A supporting structure for electrical resistance elements comprising a pair of coaxial spaced disks each having peripheral slots about the periphery thereof, ;a resistance wire wound in zigzag fashion in said slots and alternating between said disks so as to present the appearance of a cage, and a filament of insulating material encircling said cage to secure said resistance wire from displacement from disks.

6. Asupporting structure for electrical resist ance elements comprising a pair of coaxial spaced disks each having .aplurality of openi gs extend ing about the periphery thereof, a resis' nce wire wound in zigzag fashion in said openings and alternating between said disks so as to present the appearance of a cage, and a of insulating material encircling said cake at each of said disks to secure said resistance wire from displacement from said disks, said filament being threaded through the openings extending about the periphery of each disk.

'7. A supporting structure. for electrical resistance elements, comprising a pair of coaxial supporting members eachhaving a plurality of protuberances about the periphery thereof and e tending radially therefrom, a resistance wire wound. zigzag fashion over protuberances andalternating between said supporting members so as to present the appearance of .a cage, and a. filamentof insulating material encircling said cage at eachof said supporting members to secure said resistance wire from displacement from said protuberances,

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,110,602 Thomas Sept. 15, 1914 1,266,570 Farnsworth May 21, 1918 2,298,315 Siegel et al l3, 194:2 2,428,003 Beam et al Sept. 30, 1947 

